How Does an External Modem Work?

What is an External Modem?

A modem, short for modulator-demodulator, is a device that allows digital data to be sent and received through a phone line, allowing computers to communicate over large distances. An external modem is a modem that consists of a self-contained case that does not need to be attached inside a computer case. Connecting a computer to the internet requires some form of internet gateway, a device most commonly used by private users. When the internet first came into use, internal modems were common, but externals have become more prevalent in recent years.

The function of a modem

Both external and internal modems serve the same function and work in the same way. They take digital data from a computer and turn them into analog signals that can be sent over phone lines, to be received by another modem, and changed back into digital data. When you connect to another computer using a modem, you initially hear some high and low pitched pinging noises. This is the other computer sending data in the form of audible analog signals, where one pitch represents the number 1, and the other represents the number 0; these are the two numbers used in binary, the language computers use to process data.

When two computers communicate

As two computers communicate over a phone line with modems, each is simultaneously converting digital data into analog data to be sent out, as well as converting incoming analog data into digital data. As data is being sent, the modems also communicate as to what data they ultimately sent and received to make sure that the data matches up. Since phone lines were designed to carry sound and not data, this redundancy check is important to make sure that data received is not corrupted.

External vs. Internal modems

Though both types of modems work in the same way, each has its benefits. No installation is required with an external modem, making them easier to set up. As a result, it is much easier to change the connection of an external modem from one computer to another. External modems also have lights that display which parts of the device are in operation and weather it is receiving power. The benefits of internal modems is that they are usually less expensive, and do not require the use of an Ethernet port, since the internal card is attached to the computer through a peripheral card slot instead of through an Ethernet port.